I am looking for a NP231 with a spline count of 23 I think not the 21 count smaller number.
Will
I have a "Parts" case with the 23 spline input shaft. The case is cracked at the front output bearing so it will not hold the front output shaft in place. I bought this case because it was rebuilt with a SYE, Didn't know it was cracked until after wheeling it! I swapped my old complete front case half with this one, so this input shaft is the rebuilt one. If you're mechanically inclined you can unbolt and swap out the input assembly into your existing case. $50 for the "complete" case.
Unless you need the complete case, then I just typed all this for nothing.
Rock